What does 686 stamped on a ring mean?

The number "686" stamped on a ring typically indicates the metal's purity and alloy composition. In this case, it usually signifies that the ring is made of 18K gold, which consists of 75% gold and 25% other metals. The "686" designation is a specific hallmark used in certain countries to denote this quality of gold. Always check with a jeweler for precise identification and authenticity.